# US 7,609,363 B2 · Helical optical pulse stretcher

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- Number: US 7,609,363 B2
- Document ID: US7609363B2
- Status: Granted
- Kind: B2
- Application number: 11/944,307
- Filed: 2007-11-21
- Published: 2008-03-20
- Granted: 2009-10-27
- Earliest claimed: 2004-05-24
- Assignees: ASML Holding N.V.
- Inventors: Michael M. Albert
- Web page: https://patentgrep.com/patent/US7609363B2

## CPC

- G03F 7/7055: {Exposure light control in all parts of the microlithographic apparatus, e.g. pulse length control or light interruption}
- G03F 7/70041: {by pulsed sources, e.g. multiplexing, pulse duration, interval control or intensity control}
- G03F 7/70058: {Mask illumination systems}
- H01S 3/0057: {Temporal shaping, e.g. pulse compression, frequency chirping (soliton generation and propagation G02F1/3513, H01S3/063 and H01S3/108)}
- Y10S 372/70: Optical delay
- G03F: PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR; (phototypographic composing devices B41B; photosensitive materials or processes for photographic purposes G03C; electrophotography, sensitive layers or processes therefor G03G)
- H01S: DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
- Y10S: TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS

## Abstract

A lithographic system and method using an illumination system, a single pass pulse stretcher, an optical system, a patterning device and a projection system. The optical system is arranged around the single pass pulse stretcher. A beam enters the single pass stretcher and is reflected in a helical path using the optical system for multiple passes through the single pass pulse stretcher. The single pass pulse stretcher can include two 90° prisms, with a beam splitter located therebetween. The optical system can include first and second prisms. At least one of the first and second prisms can be a roof prism. The first and second prisms can have at least one surface oriented so as to direct the beam into the helical path. The optical system can have at least one mirror, or a plurality of mirrors.

## Claims

### Claim 1

A lithographic apparatus, comprising:
an illumination system configured to produce a beam of radiation;
a single pass pulse stretcher;
an optical system arranged around the single pass pulse stretcher such that the beam of radiation is directed in a helical path for two or more passes through the single pass pulse stretcher to produce a pulse stretched beam;
a patterning device configured to pattern the pulse stretched beam; and
a projection system configured to project the patterned beam onto a target portion of a substrate.

### Claim 2 (depends on 1)

The lithographic apparatus of claim 1, wherein the optical system comprises a first prism and a second prism.

### Claim 3 (depends on 1)

The lithographic apparatus of claim 1, wherein the single pass pulse stretcher comprises:
a beam splitter; and
two 90° prisms,
wherein the beam splitter is located between the two 90° prisms.

### Claim 4 (depends on 2)

The lithographic apparatus of claim 2, wherein first and second prisms are roof prisms.

### Claim 5 (depends on 2)

The lithographic apparatus of claim 2, wherein the first and second prisms have at least one surface oriented so as to direct the beam of radiation into the helical path.

### Claim 6 (depends on 1)

The lithographic apparatus of claim 1, wherein the optical system comprises a mirror.

### Claim 7 (depends on 1)

The lithographic apparatus of claim 1, wherein the optical system comprises a plurality of mirrors.

### Claim 8

A method, comprising:
stretching a beam of radiation such that the beam of radiation is directed in a helical path using an optical system arranged around a single pass pulse stretcher for two or more passes through the single pass pulse stretcher to produce a pulse stretched beam;
patterning the pulse stretched beam; and
projecting the patterned beam onto a target portion of a substrate.

### Claim 9 (depends on 8)

The method of claim 8, wherein the optical system comprises a first prism and a second prism.

### Claim 10 (depends on 9)

The method of claim 9, wherein the first and second prisms are roof prisms.

### Claim 11 (depends on 9)

The method of claim 9, wherein the first and second prisms have at least one surface oriented so as to direct the beam of radiation into the helical path.

### Claim 12 (depends on 8)

The method of claim 8, wherein the single pass pulse stretcher comprises a beam splitter between two 90° prisms.

### Claim 13 (depends on 8)

The method of claim 8, wherein the optical system comprises a mirror.

### Claim 14 (depends on 8)

The method of claim 8, wherein the optical system comprises a plurality of mirrors.